samba - Jul 2003 - Windows XP / Username "Guest" in disabled drop down

I am using a Windows XP client to connect to Samba 2.2 running on RedHat Linux
9.0, and I am trying to understand the following behaviour:
 
Connecting to the EXAMPLE share (smb.conf given below) - with "guest ok =
no" - from the command line (ie Windows -> Run ->
\\xxx.xxx.xxx.xxx.\EXAMPLE , where xxx... is the ip address of the Linux box)
from Windows 2000, I am prompted for username and password, and can connect
successfully as "content" or "manager". Connecting from
Windows XP, however, the username defaults to xxx.xxx.xxx.xxx\Guest and the
username field is disabled. Thus, I can not connect at all.
 
Using NET USE... or Tools -> Map Network Drive does not present the same
problem. These options are not "allowable" solutions to my particular
problem, however.
 
Any information gratefully received...
 
Regards
 
Peter
 
#### smb.conf ####
 
[global]
 
        workgroup = MYGROUP
        server string = Test Machine
        netbios name = TESTMACH
        log file = /var/log/samba/log.%m
        max log size = 50
        security = share
        encrypt passwords = yes
        smb passwd file = /etc/samba/smbpasswd
        socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
        dns proxy = no
        guest account = smbguest
        veto files = /.htaccess/
 
[EXAMPLE]
        comment = EXAMPLE
        path = /usr/local/content/EXAMPLE
        write list = manager content
        guest ok = no
        read only = yes
        available = yes
        create mode = 664
        force create mode = 664
        directory mode = 0775
        force directory mode = 0775
 
###############
 
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